Add models with the Megatron-LM backend

Last updated: 04/25/2025.

Model

If use latest verl, we have direct support of GPTModel for Megatron backend. You can use the similar way of using Megatron to pretrain custom models. We list the steps here:

1. Find model_initializer.py <https://github.com/verl-project/verl/blob/main/verl/models/mcore/model_initializer.py>_
2. If your model is configurable by TransformerLayerSpec , you can directly use GPTModel. Otherwise, Please implement a new ModelLayerSpec and ModelLayer here.
3. Use the right LayerSpec , TransformerConfig and HuggingfaceConfig as arguments to initialize the GPTModel.
4. Return the model at last.